(1)
Except as provided in Article 9.9.4.5., where exterior walls of a building meet at an external angle of 135° or less, the horizontal distance from an unprotected opening in one exterior wall to an unprotected opening in the other exterior wall shall be not less than 1.2 m, where these openings are
(a)
in different fire compartments, or
(b)
in different dwelling units, ancillary spaces or common spaces in a house with a secondary suite.
(2)
Except as provided in Sentence (3), the exterior wall of each fire compartment referred to in Sentence (1) within the 1.2 m distance shall have a fire-resistance rating not less than that required for the interior vertical fire separation between the compartment and the remainder of the building.
(3)
Where interior walls between dwelling units, ancillary spaces or common spaces in a house with a secondary suite are not constructed as fire separations, the exterior wall of each dwelling unit, ancillary space or common space referred to in Sentence (1) within the 1.2 m distance shall be finished on the interior with not less than 15.9 mm thick Type X gypsum board.